Apparatus for setting storage battery plates



Nov. 24, 1936. E. w. SMITH ET AL 2,062,193

APPARATUS FOP SETTING STORAGE BATTERY PLATES 7 Filed Nov. 3, 1952 Fateniecl Nov. 2 3%36 APPARATUS FOR ETTING STORAG BATTERY ZPLATES Edward W. Smith and Clarence A. Hall, Philadelphia, Pa, assignors to The Electric Storage Battery Company, Philadelphia, Pa, a corporation of New Jersey Application November 3, 1932, Serial No. 641,037

4 Claims.

The composition of the paste used for filling the grids of a storage battery plate is usually such that certain chemical reactions take place after the paste has been applied to the grid which tend 5. to harden the material. This hardening or setting process is somewhat analogous to that which occurs in cement after it has been mixed with water and should be carefully distinguished from the hardening due to drying or expelling of the moisture. In the case of a freshly pasted storage battery plate as usually manufactured, if any considerable amount of true drying occurs by the expulsion or evaporation of the water before the true setting or hardening due to chemical reaction has taken place, the material will shrink and crack. If, however, the paste isv allowed to set by chemical reaction before any substantial amount of drying takes place, the hardening efiect of this setting will prevent subsequent shrinkage and cracking when the moisture is expelled. The apparatus disclosed by the applicants is designed to carry out this process of first setting without drying andsubsequent drying in a practical and commercial manner. The setting process, which is hastened by elevating the temperature, takes place in the first of. the series of ovens where heat is applied in the presence of a highly humid or even saturated atmosphere in which there is no tendency for moisture to be driven out of the plates. The plates are retained in this oven until the setting has progressed sufiiciently to prevent shrinkage and cracking when the subsequent drying takes place, and this subsequent drying is carried out in one or more ovens through which the plates are then passed. The apparatus disclosed by the applicants is especially designed to control the steps in this process and they co-operate to produce the final result.

One of the novel features of the disclosure is the introduction of means for spraying the plates with a setting and hardening fluid as a further means for insuring that the setting is suitably effected. This setting fluid as disclosed contains material in solution, such as sulphuric acid or ammonium sulphatawhich reacts with the material of the paste to produce a hardening effect by chemical reaction.

In dryingstorage battery plates subsequent to pasting, it is desirable to perform two distinct steps; 1st to heat the plates throughout to a relatively high temperature short of the boiling point without the removal of a substantial portion 01 the moisture, using for this purpose a very humid atmosphere; 2nd to cause evaporation to take place by maintaining a high temperature in an unsaturated atmosphere. The process may be carried to the point of complete dryness, or it may be carried only so far as to set the paste 7 sufiiciently that when the plates are stacked upon one another their surfaces will not adhere.

The present invention includes apparatus for conveniently and economically carrying out the above drying or setting process, and is especially adapted for use in connection with a plate lifter, forming the subject of application for patent Serial No. 641,036 filed by said Edward W. Smith for a machine for turning. storage battery plates from horizontal to vertical position.

The present invention also includes the improvement in the process of drying storage battery plates which consists in applying liquid, in addition to the liquid contained in their paste, to the storage battery plates at some stage in the drying operation which includes the application of heat.

In the following description reference will be made to the accompanying drawing forming part hereof and in which Figure 1 is a diagrammatic view illustrating principally in vertical section apparatus embodying features of the invention.

Figure 2 is a transverse sectional view of the same, and

Figure 3 is a view similar to Fig. 1 illustrating a. modification. a

Referring to Fig. 1, 2| and 24 indicate four conveyor chains having opposed projecting pins, suitable to engage storage battery plates P and hold the same in parallel side by side vertical plane arrangement, in the general manner described in, the application above referred to.

' These conveyor chains pass through an oven-like enclosure divided into compartments I and 2 and.

finally through a short open run 3, roughly about as long as one of the compartments. At the'very end are a couple of rails 25 so placed as to support the plates by their lugs, (after they are released by the conveyor chains) thus leaving them in a convenient position for removal in bulk. I

The oven compartments 1 and 2 are substantially alike; each is made with a water tightbottom, is provided with a steam coil 4 5 or other heating means, and with a. fan 6 and I for circulat ing the atmosphere of the oven through the column of plates. The intermediate. and end partitions of the oven compartments are provided with openings for the passage of the plates, such openings fitting the profile of the plates as closely as practicable, and having a short tunnel like pro- Jection Ill-ll-IZ. It will be noticed that as there are always one or more plates at a time in each of these short tunnel openings, the opening is continually closed so as to minimize intermixing of the atmosphere through the opening.

Adjacent to the final run of conveyor chains in the open air, at'3, there is placed a fan 88 arranged to blow a stream of air directly onto lower part, so as to partly or entirely cover the steam coils, the water of course becoming heated thereby. The fan 6, by means of the pipes shown, delivers a current of humid air directly down upon this heated water, the air thereby becoming heated, and very strongly humidified or even saturated. Passing upward this stream of air heats the column of plates through which it blows, withoutat the same time causing any appreciable drying, owing to its high humidity. After passing through the plates, the air is recirculated.

In the second compartment, there is much less water at the bottom, so that part of the coil is directly exposed to the air. The air circulated by the blower 1 hence rises up through the compartment and through the column of plates at .an elevated temperature and in a partly saturated condition, ready to absorb moisture from the plates, while maintaining them at an elevated temperature.

Further control of the humidity in both ovens is provided by means of damper openings 8 and 9, which permit the discarding of a portion of the circulating atmosphere, to be replaced by fresh air drawn in through the tunnel openings Ill-42, or through other openings which may be supplied. I

In the final run of the conveyor 3, the plates are subjected to a mild draught of atmospheric air, which still further dries and at the same time cools them, so that by the time they reach the racks 25, they may be removed and piled on top of one another without danger of sticking together, even though not entirely dry.

As an example of a satisfactory set of conditions, we may give the following figures:

1st Compt Temp. 170180 F. 90100% Humidity 2nd Compt Temp. -170 F. 40- 60% Humidity Time of plates in each compartment 3-5 minutes.

When the plates have been through the two compartments and have passed over the fan '8 and arefinally delivered on the rails 25, they are still moist, but the paste has become set" to such 'extent that it is no longer sticky, and hence the plates may be piled for storage, ready for final assembly.

It should be noted that this processor setting is very critical, and that careful control of the conditions is at all times necessary. The temperature and humidity in the compartments have to be variedto suit the thickness of plates, the composition of the paste, and even the atmospheric conditions: hence it is impossible to quote figures which will fit all cases, and these given merely happen to have been satisfactory for a particular kind of plates.

It also should be noted that while we have shown an oven containing two compartments, it may be of advantage to use further subdivisions so that the progressive changes of temperature and humidity may take place more gradually.

As a further refinement in this process we refer to Fig. 3, which shows a modification by which the plates are passed through a cascade of a fluid which exercises a strong hardening or setting action upon lead oxide. The plates are first passed through the hot humid oven compartment l, where they are heated without substantial drying; next they are passed through a double cascade-2|, which momentarily floods both plate surfaces; after-which they pass on through further oven compartments, omitted from the figure, to avoid confusion, but substanin a trough 22 and thence returns by gravity to the tank 23. The tank 23 serves two main purposes; 1st it permits of adjustment of the strength of the solution, which constantly tends to become weaker;' 2nd it furnishes means by heating coil 21, of regulating the temperature of the setting solution to conform to that of the plates.

In the drying of freshly pasted storage battery plates, unless care is exercised the paste has a tendency to shrink and to crack. The above described method of first heating in humid atmosphere and then drying in a partially saturated atmosphere makes it. possible to accomplish adequate drying without cracking; it is still a critical process, however, which needs very careful regulation. By the employment of the eascade, as above described, the limits within which successful setting and drying are accomplished are very much widened, and hence satisfactory results may be obtained without such extremely close control as is otherwise necessary. The drying may be carried to completion if desired; but for ordinary purposes it is quite sufficient to set the paste thoroughly, thoughv without completely drying it.

The dousing of the plates thus described has been successfully practiced prior to the plates entering any of the heating compartments and also between the 1st and 2nd compartments, so we do not wish to limit its use to the latter position, above described.

therethrough conforming closely to the profile of said plates, a conveyor arranged to support plates in a vertical position with their pasted surfaces opposite each other and extending through said oven compartments and said openings, means in the first of said compartments for maintaining an atmosphere saturated with water vapor at an elevated temperature and at atmospheric pressure, means in saidsecond comace-ales partment for maintaining an under-saturated atmosphere at elevated temperature and at at- .nospheric pressure, and means adjacent the first compartment for wetting the plate surfaces with a. setting fluid before drying has begun.

2. Apparatus for drying the paste in freshly pasted storage battery plates, said apparatus comprising in combination, two oven compartments having enclosing walls, a conveyor arranged to support plates in a vertical position with their pasted surfaces opposite each other and extending through said oven compartments, the lower portions of said compartments forming a receptacle for liquid whose free surface isdirectly beneath and directly exposed to the plates on saidconveyor, heating means extending into the lower portion of said compartments adjacent the liquid therein, bypass conduits having inlets from the upper part of said compartments and outlets in the lower part of said compartments directed towards the free surfaces of the liquids in said compartments, and means in said bypass conduits for circulating fluid through said conduits.

3. Apparatus for drying the paste in freshly pasted storage battery'plates, said apparatus comprising in combination, two oven compartments having enclosing walls, a conveyor arranged to support plates in a. vertical position with their pasted surfaces opposite each other and extending through said oven compartments, the lower portions of said compartments forming a receptacle for liquid whose free surface is directly beneath and directly exposed to the plates on said conveyor, heating means extending into the lower portion of said compartments adjacent the liquid therein, bypass conduits having inlets from the upper part of said compartments and outlets in the lower part of said compartments directed towards the free surfaces of the liquids in said compartments, means in said bypass conduits for circulating fluid through said conduits, and a'fan mounted adjacent said conveyor on the exit side of said compartments so as to blow a stream of air directly onto and through the plates on said conveyor.

4. Apparatus for drying the paste in freshly pasted storage battery plates, said apparatus comprising in combination, two oven compartments having enclosing walls, a conveyor arranged to support plates in a vertical position with their pasted surfaces opposite each other and extending through said oven compartments, the lower portions of said compartments forming a receptacle for liquid whose free surface is directly beneath and directly exposed to the plates on said conveyor, heating means extending into the lower portion of saidcompartments adjacent the liquid therein, bypass conduits having inlets from the upper part of said compartments and outlets in the lower part of said compartments directed towards the free surfaces of the liquids said conveyor and providing a cascade of setting liquid falling upon the plates on said conveyor.

EDWARD w. sm'rn; CLARENCE A. HALL. 

